Solvent-Mediated Photoinduced Electron Transfer in a Pyridinium Ionic Liquid

Vieira, Rebecca C.; Falvey, Daniel E.

doi:10.1021/ja077797f

Cited by 60 publications

(36 citation statements)

References 26 publications

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“…The higher rates in ILs may be realized in more organized media, such as IL crystals. A similar phenomenon was observed by photoinduced electron transfer in ionic liquids [18].…”

Section: Aqs+ Bpy • Aqssupporting

confidence: 81%

Electron transfer in N-butylpyridinium tetrafluoroborate ionic liquid by pulse radiolysis

Zhang

Cao

et al. 2013

Chin. Sci. Bull.

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The radiolysis behavior of neat pyridinium ionic liquids (ILs) and their aqueous solutions was investigated using nanosecond pulse radiolysis techniques. Radiolysis of the ionic liquids, such as N-butylpyridinium tetrafluoroborate (BuPyBF 4 ), resulted in the formation of solvated electrons and organic radicals. Solvated electrons reacted with the pyridinium moiety to produce a pyridinyl radical, which can transfer electrons to various acceptors. The electron-transfer rate constants of the solvent-derived butylpyridinyl radicals in BuPyBF 4 and in several compounds (for example, duroquinone, 4,4′-pyridine, benzophenone, and 1,1′-dimethyl-4,4′-bypyridinium dichloride) (k of the order 10 8 L/(mol s) were lower than those measured in water and in i-PrOH but were significantly higher than the diffusion-controlled rate constants estimated based on viscosity. The electron-transfer rate constants in neat BuPyBF 4 were one order of magnitude faster than the diffusion-controlled values. This finding suggests that BuPyBF 4 acts not only as solvent but also as active solute, such as in solvent-mediated reactions. These reactions result in electrons reaching their final destinations via intervening pyridinium groups without requiring the diffusion of a specific radical. In recent years, ionic liquids (ILs) have become the most studied class of solvents and are considered valid potential substitutes of many volatile organic solvents [1][2][3]. ILs are salts and thus are ionic compounds in liquid form at or near room temperature. ILs exhibit several unique thermophysical properties owing to their asymmetrical structures and the charge dispersion of their organic and inorganic ions. These compounds do not evaporate at ambient temperature and have relatively high thermal stability, high ionic conductivity, and large liquid temperature range. ILs also demonstrate excellent solvent quality for many types of compounds. Traditional methods of chemical kinetics must be applied to the study of IL chemical reactivity to exploit properly the potential of these solvents. In this work, pulse radiolysis techniques were used to observe the electron-transfer reactivity of N-butylpyridinium tetrafluoroborate (BuPyBF 4 ) ILs with several transient species. Pulse radiolysis is a technique where samples are irradiated using a laser-generated beam of high-energy electrons and the species (electron, radicals, cations, etc.) are studied through their absorption spectra [4]. This technique is useful for studying reaction rates, particularly for very fast reactions such as redox reactions and reactions that contain short-lived species. Neta and co-workers [5,6] compared the reaction rate constants of ILs with those of traditional solvents (acetonitrile and alcohol) to determine the stability of ILs as alternative reaction solvents for specific reactions. They studied reaction kinetics in imidazolium salts and in methyltributylammonium bis (trifluoromethylsulfonyl)imide [7][8][9]. However, to the best of our knowledge, only a few studies focused on t...

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“…The higher rates in ILs may be realized in more organized media, such as IL crystals. A similar phenomenon was observed by photoinduced electron transfer in ionic liquids [18].…”

Section: Aqs+ Bpy • Aqssupporting

confidence: 81%

Electron transfer in N-butylpyridinium tetrafluoroborate ionic liquid by pulse radiolysis

Zhang

Cao

et al. 2013

Chin. Sci. Bull.

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“…The PET reaction in acetonitrile medium was found to fall in the normal Marcus region. However, PET reaction rate in some pure ionic liquids was also found to fall in the normal Marcus region showing Rehm-Weller behavior[23,24]. But in this case the inherent heterogeneous behavior of the ionic liquid is responsible for getting such type of inversion which we have observed previously in various heterogeneous environment like micelle, reverse micelle, cyclodextrin, etc.…”

mentioning

confidence: 77%

“…We have already reported PET in an aliphatic ionic liquid DAF using the same donor acceptor pair and observed saturation in the electron transfer rate vs free energy correlation curve [22]. Falvey and co-worker have studied PET reaction in two room temperature ionic liquid and observed that the PET reaction rate follow the Rehm-Weller behavior [23] and they have also studied solvent mediated PET in a pyridinium ionic liquid [24]. Recently LyndenBell have investigated some simulation studies of model systems of two ionic liquids and compare with acetonitrile to judge the applicability of Marcus theory in ionic liquids [25,26].…”

Section: Introductionmentioning

confidence: 88%

Photoinduced intermolecular electron transfer in a room temperature imidazolium ionic liquid: An excitation wavelength dependence study

Sarkar

Pramanik

Ghatak

et al. 2011

Chemical Physics Letters

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“…The pyridinium ionic liquids have already been successfully applied in many processes. The example may be the photoinduced electron transfer (PET) [1] and conductive liquids in electrochemistry. The others, such as the accelerated amine-catalyzed Morita-Baylis-Hillman reactions [2], recyclable and highly efficient organocatalysts for the asymmetric Michael addition reactions [3], the tetrahydropyranylation of alcohols [4], the Friedel-Crafts alkylation reactions [5], the Diels-Alder reactions [6], Grignard reactions [7], or the Fischer esterification [8].…”

Section: Introductionmentioning

confidence: 99%